I just read several times over the book, re-read again and again - and it makes perfect sense and fits in many observations I did. It explains a lot.

I think, there could be something into it for hive improvements. Making it a condenser hive - an even better one as the construction hive by Clark.

For example we could use a clay roof in summer during flow.

It also gives some explainations why bees in hollow trees survive varroa, while transfered in hives the bees die off varroa. Condensation properties of the hive may be the difference! Because without condensation, the water has to be carried in - this may lead to less brood food sap (gelee royal for the workers, what is the right word again?). Because the brood food is made with pollen and water!

Missing water through condensation, little water collection during a main flow may lead to less brood food per cell, making a difference to varroa population! Because the less brood food, the earlier the mite awakes from it's sleep in the brood food and starts oogenisis. Leaving more time to reproduce, multiplying itself from 1.7 up to 3-4 times.

After a quick read of Clark's book, I see he mentions two further facts:

When moisture from the hive condenses IN the hive, the heat that is given up during condensation ('latent heat') remains within the hive. This heat helps to maintain the temperature of the hive rather than being lost to the outside air. Varroa doesn't like warm conditions.

The air inside containers remains drier if any moisture that is present can condense on the walls of the container. Clark uses the example of refrigerators staying dry as long as moisture can condense on the walls (and drain out through that little hole at the bottom of the back).

On this analysis, a hive that has an impermeable inner coating (such as propolis) on its walls stays both warmer and drier than one that has vapour permeable walls or a vapour permeable quilt.

Isn't this the opposite of the idea behind the permeable Warre quilt?

I'm off to have a read about Roger Delon's Stable Climate hives ....._________________Gareth

One Kilogram of honey needs the evaporation of three kilogram of water since nectar contains about 60 to 80 % of water and honey just 20 %.

To suck up the 3,000 gram of water at an air temperature of 20 degree Celsius about 300 cubic metre are needed.

One empty (!) Warré hive box holds 0.02 cubic metre!

You need the air mass of 15,000 empty Warré hive boxes, to get rid of that water. Empty hives and of course the air mustnot contain any water, which is not the case in outdoor conditions. So you need even more air to suck up that water.

That doesn't work through ventilation, not even with heavy overdose ventilation.

Think of the humid conditions in May, and this exactly explains, why swarms take off after rainy days.

mmm am trying to get my little brain round this one
It appears from what you are saying Bernard that the bees
a) have a lot of work to do to ' dry out ' the honey
b) heat and air flow is the key to this .

I am assuming that bees in 'super organism ' mode can regulate the conditions in the hive . Is this where the Warré Quilt comes in ?
What can we do to help the bees ? Would replacing the quilt material help ?
A summer quilt ( soaking up water Charcoal ? Wool ? something like a wick ) vs a winter quilt( insulation )

Just another thought . If the Bees are living in a tree that is still living ,would the tree its self absorb water from the nest ? I know trees spend a lot of energy effectivly pumping water up to and out of the leaves from the roots . An active system could remove a lot of water this way , if you do the math trees shift a lot of water around .

Not just. Heat yes. Air flow - no! The opposite. The air flow = ventilation. Ventilation is needed but just a little. Condensation actually is drying out the air! Much more than ventilation ever could. See calculation above.

So instead of a wick or sponge, you need a safe condensation surface. I guess the wall is best for this. Because the floor has a lot of debris fallen onto, which would turn into slime. Bees won't take this for food production for obvious reasons. Overhead condesation may lead to dripping water onto the bees. On the sides the condensation would be best.

So to design condensation into hives, you have to insulate just a little. I read about phase-change-material - and this where wax comes into! Wax is the perfect phase-change material. 4 cm wax coating provides heat storage like a solid 30 cm brick wall! See: http://en.wikipedia.org/wiki/Phase-change_material

So one construction element could be the coating of the inner sides with a thick layer of wax and on it a layer of rosins/propolis coating. Probably as efficient as a polystrene hive!

That would keep the heat inside the hive, making it warmer than the outside air, thus producing condensation!

Next thing would be to eliminate the over-ventilation. By making the lid and box junctions as airtight as possible.

It'd be good to have an additional surface at the wall which is cooled some way to produce condensation there - to keep the air dry and provide an inhive water source. Thinking about a window glass pane with some cooling mechanism. The window serving two purposes: condensation surface and observation possibility.

How about a substance that is cool because it is cooled by the evapouration of water . I was thinking terracota . Plants are often better in terracotta pots because they dont cook in them unlike plastic pot in hot weather, the romans stored wine in then as it kept cool . Since water will soak in there is no chance of water dripping into the hive.
Instead of the quilt a terracotta tile in summer? just a thought

This all seems to focus on the summer time when there are a lot of active bees to remove the water physically from the walls/ roof etc.

What about the winter time? I thought that condensation and moisture was the last thing that one should have in the hive! Poor ventilation, non-breathable walls, little insulation etc. all seem to point to wet hives and dead colonies! This is shown by the greater winter survival with open, mesh bottoms of hives. Skeps too allow for dissipation of moisture through the hive wall and skeppists report very happy, lively hives.

I am not saying the condensation theory is wrong, I just cannot see how these opposites can both be true.

(By the way, I asked my local beekeepers if they noticed much difference between the winter survival performance of wooden and poly hives and there was very little to distinguish between them. Poly hives being only slightly better. I think the advantages are mainly in lighter weight, lack of rot/maintenance and perhaps price.)

That study is available here and shows that, at 70% humidity, Varroa reproduce at the highest rate, whereas at 80% they almost stop reproducing completely. In other words, every 1% increase in humidity above 70% in the brood area hurts Varroa.

This suggests that a perfect hive for Varroa control would be one that allows the bees to maintain as a high a humidity as possible in the brood cells.

So

Small entrance
No through ventilation
No bottom screen
Old comb if possible (to buffer humidity)
Small cells??
Non-porous hive walls??

Gareth hit on this above but I would add the propolis to the mix. We know they want to coat the entire inside of the hive with it. That would provide the vessel for condensation on the walls. The high humidity coupled with ample propolis may provide an inhospitable environment for mites and other vectors as well. The unanswered question with survivor bees in a tree is; did it take a couple of tries to get it up to a healthy level. Or do the bees start in a tree and die the first season, while providing a jumpstart for a swarm to move in the following season. This second colony may also succumb to mites but provided the additional work on the hive that will catapult swarm no 3 to become successful survivor bees. If these 3 swarms came from the same survivor colony and over three seasons colonized another tree then they were successful. Some folks would view this as 2 failures in a row; I say it all just natural progression.

Some great thinking going on here guys, thanks for starting it Bernhard. I think I'm a believer already as it serves to reinforce the 'hive atmosphere' argument (Nestduftwärmebindung) on which I'm totally sold.

Can I ask what you mean by an 'already built up environment' Bernhard? Do you just mean a nest where previous occupants have already plastered the walls with propolis/wax or are you also anticipating some previous combs left behind as well? Again this all makes so much sense.

Prof. Seeley's maintains that the survival rate of new swarms in Feral colonies is 25%. Presumably this could be prime or secondary, but difficult to study in tree colonies 7 metres high. Conditions and sites of hives in feral colonies seem to require South facing entrances and a distance of approximately 250 metres between colonies. Once established the forest communities have increased in spite of varroa over the 30 year plus period.
Barry

This fits nicely with my plan for lowering the floor mesh and adding a deep layer of wood shavings, which would absorb excess moisture and maintain a higher humidity. The one hive I have done this on so far is certainly doing well so far.

Pics here - http://www.biobees.com/images/?dir=deepFloor - although MKII will simply be a removable extension of the side walls using 4"x1" timber. This will also allow bees to extend their comb a little deeper without feeling a draught.

Last edited by biobee on Tue Jan 24, 2012 11:02 am; edited 1 time in total

Tricky... but wouldn't that be closely related to the humidity in the general vicinity of the brood nest? I already have a sensor that would fit there.

I can imagine that the humidity 'in the vicinity of the brood nest', say at its edge, might vary from that in the core brood nest and also from that inside the cells. And the humidity in the cells could itself vary between the edge and the core of the brood nest. Size of cell could be relevant, eg small worker cells vs larger worker cells vs drone cells, as well as position of the cells.

I'm not saying that a series of measurements taken over a season would not be interesting, merely that one would need to be careful about extrapolating from them._________________Gareth

Conserving wild bees

Research suggests that bumble bee boxes have a very low success rate in actually attracting bees into them. We find that if you create an environment where first of all you can attract mice inside, such as a pile of stones, a drystone wall, paving slabs with intentionally made cavities underneath, this will increase the success rate.

Most bumble bee species need a dry space about the size a football, with a narrow entrance tunnel approximately 2cm in diameter and 20 cm long. Most species nest underground along the base of a linear feature such as a hedge or wall. Sites need to be sheltered and out of direct sunlight.